1. Field of the Invention
The present invention relates to an electrode lead for an active implant, more particularly to a lead with electrodes for a pacemaker or similar device.
2. Description of the Prior Art
Modern pacemakers systems generally include an implantable pulse generator and one or several electrode leads connected to the pulse generator at the proximal end of the lead(s). The distal ends of the leads are provided with electrodes for electrical contact with the myocardium.
The pulse generator normally is implanted under the skin close to the shoulder of the patient and the leads are advanced through the subclavian vein and the vena cava for instance into the right atrium and/or the right ventricle of the heart. In order to hold the lead in place and to ensure that some or all electrodes on the lead are in contact with the myocardium, the distal end of the lead may be provided with tines or similar structures extending outwardly from the lead as for instance disclosed in PCT Application WO 98/20933. The tines or threads are for instance intended to engage the trabeculae in the apex of the ventricle.
There are several designs for facilitating the removal of leads provided with tines. One such design is disclosed in PCT Application WO 98/20933 in which the tines are designed so as to be detachable from the lead and remain attached to the trabeculae.
In other designs for attachment means for the distal end of the lead, the lead is provided with a helical thread extending laterally and outwardly from the lead, as disclosed in U.S. Pat. No. 4,550,737. The function of this design is generally similar to the function of the above design having tines as far as the function is concerned. The idea behind this design is to facilitate the insertion of the lead, particularly into the trabeculae. Retraction or explantation of the leads or any problems associated therewith is however not discussed.
U.S. Pat. No. 5,423,884 discloses a similar design to that disclosed in U.S. Pat. No. 4,550,737. This design also is provided with an external, helical thread on the outside of the lead. One embodiment thereof is designed with a helical, circumferential groove on the cylindrical outer periphery of the lead. Similar to the embodiment with the external thread, the groove is intended to facilitate the introduction of the lead into the veins and preferably is to be rotated during insertion by means of a motor. Again, retraction or explantation of the lead is not discussed.